The sensory coding deficits that follow lesions of the dorsal spinal columns do not fall into a simple framework, such as loss of detection, localization or movement perceptions. Instead they cut across these categories, revealing impairments in discrimination of force differences, movement direction, and a restricted set of spatial cues (such as size). Motor disorders have long been known to follow damge to the dorsal columns. However, with training, the only enduring motor deficits involve the performance of grasp responses. We propose to evaluate whether the dorsal columns provide a specialized set of sensory information that is critical for the execution of precise finger movements involved in active touch. Acting as a source of feedback to motor cortex, the dorsal columns may provide information that is critical to the fractionation, orientation and appropriate force adjustments for the distal extremities. We have designed a series of experiments which thoroughly test the abilities of monkeys to fractionate finger movements under optimal (visually gudied) and non-optimal (tactually guided) conditions and to incorporate finger force adjustments during these fractionated finger movements. In a separate series of experiments we examine the ability of the monkey to use the spatial and temporal cues, provided by a moving tactile stimulus, to locate its position on the surface of the palm. A major goal of this work is to provide information of direct relevance to clinical neurology and neurosurgery. A better understanding of spinal tract function is fundamental to accurate diagnosis of CNS pathology affecting the somatosensory system. Also, fundamental to an understanding of somatosensory coding mechanisms at thalamic and cortical levels is an accurate description of the functional contributions of the different spinal inputs to these regions. With strong emphasis on recovery of function over long periods of time following spinal lesions, we are attempting to build a realistic and detailed picture of the functional plasticity of the spinal cord following identified lesions.